For several years there has been a growing awareness of air and water pollution problems caused by leaking liquids such as gasoline that flow through buried pipelines such as those present at gasoline service stations. As a result, secondary containment systems have been developed for these systems. A secondary containment system typically includes a primary pipeline in which a product such as gasoline flows from an underground storage tank to a product dispenser. The system also includes a secondary pipeline that surrounds the primary pipeline. The purpose of the secondary pipeline is to contain any fluid that may leak from a damaged primary pipeline, and prevent the fluid from contaminating the surrounding ground. The secondary pipeline is generally monitored for fluid collection so that any leak in the primary pipeline can be repaired promptly.
Fittings known as bulkhead fittings or penetration fittings are generally used in combination with secondary containment systems to permit a buried pipeline to penetrate the wall or bulkhead of a containment box. Containment boxes are liquid-tight boxes associated with connections in the primary pipeline. For example, containment boxes are often provided under product dispensers, at product pumps, or at other junctions in the primary pipeline to contain any product that may leak or spill from the primary pipeline associated with such equipment. A penetration fitting prevents any such liquid that is collected in a containment box from contaminating the ground by sealing the hole in the wall through which the pipeline penetrates the wall of the containment box.
Many different types of penetration fittings have been developed. A popular type of penetration fitting is a boot made from a resilient elastomeric material which imparts flexibility to the joint between the pipeline and the containment box. One such a boot is disclosed at FIG. 22 of U.S. Pat. No. 5,297,896 to Webb. According to the Webb patent the containment box includes a pipe entry hole through which the pipeline extends. Surrounding the entry hole are a plurality of stud holes which assist in fastening the boot to the wall of the containment box. The boot is installed from the outside of the containment box and includes a flexible sleeve section extending from a sealing flange. While the sealing flange is located outside the box, the sleeve extends through the pipe entry hole and into the box. The sealing flange includes integral studs that extend through the stud holes of the containment box. The studs also extend through a plurality of holes in a compression ring located in the box. Nuts are threaded over the studs to press on the compression ring which in turn pulls the sealing flange against the outer surface of the wall of the containment box to effect the seal. The pipeline extends into the box through the flexible sleeve portion of the boot and is sealed to the sleeve portion with a hose clamp.
A similar penetration fitting is sold by Environ Products, Inc. of Lionville, Pa. This penetration fitting additionally includes a return bend in the flexible tube portion such that the sleeve is made of a flexible tube that first extends away from the containment box and then turns inward on itself to extend through the hole in the wall of the containment box. Such a return bend provides further flexibility to the boot.
Fittings with boot portions that are stepped to accommodate two different sizes of pipes are also known. Such penetration fittings allow a single fitting to seal against two different sizes of pipeline where the two pipelines are provided in a coaxial arrangement. Such penetration fittings can also include inserts that can be clamped in place within the flexible tube to allow a single penetration fitting to accommodate different sizes of pipelines. Examples of such penetration fittings and inserts are those sold by Total Containment, Inc. of Exton, Pa.
Because prior art penetration fittings include a boot made from a resilient material, the boot can periodically crack or tear. If the integrity of a penetration fitting is compromised due to a crack or tear in the boot, it must be replaced. However, one important problem with prior art penetration fittings is that they generally cannot be easily removed and reinstalled. Because such a penetration fitting is installed on the containment box from the outside, excavation is required to put a new penetration fitting in place. Such excavation can lead to extensive maintenance costs as well as prolonged downtime of a service station.